OLED (Organic Light Emitting Diode) display devices have advantages of self-emission, low driving voltage, high luminous efficiency, short response time, high definition and contrast, large viewing angle, and flexible display, and are more and more widely used.
At present, main problems faced by OLED display devices in their application are short service life and severe parameter variations. Brightness of an OLED is determined by a current flowing through the OLED, but it is hard to realize control of a current. Therefore, accurate control of an OLED is always a core issue in the field. In the prior art, a compensation structure is usually provided to compensate a pixel driving circuit of an OLED display device.